1. Field of the Invention
The instant disclosure relates to a developer spraying device, and more particularly, to a developer spraying device for reducing usage quantity of developer.
2. Description of Related Art
The photolithography technology playing a key role in forming sophisticated circuit patterns on modern semiconductor wafers. In general, a photoresist film is deposited onto a substrate wafer during photolithography process and thereafter pattern-exposed to lithographic equipments in order to transcribe a selected circuit pattern thereon. The photoresist is subsequently processed with a developer solution to obtain a resist pattern corresponding to the transcribed pattern. The developer is used to chemically react with the photo-resist and remove the relatively more soluble areas thereof, thus leaving behind the remaining image pattern which then serves as a photo-mask for etching multiple semiconductor wafer layers.
In order to form desired patterns on a substrate, the photoresist is processed during the development step with a solution that is applied in a highly controlled manner. The application of photo-resist or resist development is carried out while a semiconductor wafer is rotated at various speeds and stopped intermittently at preselected time intervals to ensure the deposition of a photo-resist layer of substantially uniformed thickness. For example, the wafer may be rotated while a developing solution is dispensed onto the wafer from the discharge port of a spraying nozzle. A thin film of developing solution may then be formed with a relatively uniform thickness across the surface of the wafer. Both the wafer and the developer film formed thereon are held stationary thereafter for a predetermined time interval so that developing solution remains in intimate contact with the resist-coated wafer in order to develop a light-exposed latent image thereon. Upon completion of this step in the development process, pure water or other rinsing solutions can be supplied from a washing liquid supplying nozzle onto the surface of the wafer. The pure water or rinsing solution may eventually be scattered off by rotating the wafer at a relatively high speed to spin dry the surface of the wafer to complete this stage of wafer processing.
There are several common methods for developing a photoresist patterned image. For example, multiple wafers may be batched-immersed and agitated in a developer bath during a process known as immersion developing. This development process has certain advantages including high throughput capabilities. However the exposure time of the resist to the developer is relatively long and the overall process typically lack the sophistication and precision in higher level of critical dimension control required by processing more densely populated semiconductor wafers. Alternatively, in spray development, the developer can be sprayed onto a resist while the wafer is spun at a relatively high speed. Each wafer is individually treated with its own dose of developer solution. While spray development is generally an effective method to dissolve resist, it is often difficult to control the precise and uniform application of the developer to the wafer through the spray nozzle. During application of the developer, a portion of the solution may be sprayed outside of the wafer surface and wasted. Uneven exposure to developer may also adversely affect critical dimension control.
Referring to FIG. 1A, which shows a perspective, schematic view of a developer spraying device used to spray developer. When the developer spraying device A passes through (shown as the direction of the arrow in FIG. 1A) the top of wafer W, the developer D which the developer spraying device A carries can be sprayed on the surface of wafer W.
However, please refer to FIG. 1B, which shows a schematic view of developer coated on and outside the top surface of a wafer. Because the nozzles at the bottom of the developer spraying device A lines up straight, and the top surface of the wafer W is circular, when the developer spraying device A passes through the top of the wafer W, the developer D which the developer spraying device A carries will be sprayed on not only the top surface of the wafer W, but also the developer D′ will be sprayed on the outer surrounding region outside the top surface of the wafer W. Therefore, when the developer D′ is sprayed at the outer surrounding region outside the wafer W, the outer surrounding region becomes a redundant developer spraying region, which wastes developer and does not meet the requirement of modern environmental protection.